Lobular Carcinoma in Situ (LCIS)

This information will help you understand what lobular carcinoma in situ (LCIS) is, what it means for your risk of developing breast cancer, and what screening and prevention strategies may be right for you.

What is LCIS?

LCIS is a term used to describe a breast change characterized by an increased number of cells inside the lobules of the breast. The breast lobules are the small round sacs that produce milk. The term “in situ” means “in place,” meaning those cells are only in the lobules. Although the term LCIS includes the word “carcinoma,” which is another word for cancer, LCIS is not breast cancer. However, LCIS does increase your risk of developing breast cancer.  If your biopsy shows that you have LCIS, your risk of developing a breast cancer in either breast is approximately 1% to 2% per year, gradually increasing to 10% to 20% in 10 years.
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Breast Cancer Screening

Women with LCIS should have regular breast exams and breast imaging.  You and your doctor will decide what type of breast imaging is best for you, based on your personal history as well as your breast density.  At Memorial Sloan Kettering, we recommend a physical exam with a breast specialist every 6 to 12 months, as well as breast imaging every year.
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How to Lower Your Risk for Invasive Breast Cancer


Taking certain medications to help lower your risk of developing breast cancer is known as chemoprevention. Chemoprevention for breast cancer means taking a pill once a day for 5 years.  Studies have shown that these medications may lower your risk of breast cancer by more than 50%.  Talk with your healthcare provider about the risks and benefits of these options so you can choose the one that is best for you.

Tamoxifen and raloxifene  

Tamoxifen and raloxifene are medications that lower the risk of breast cancer by blocking the effects of estrogen, a hormone that influences the development of many breast tumors. These medications only reduce your risk of developing estrogen receptor-positive breast cancer, which is the most common type. They will not reduce your risk of estrogen receptor-negative cancers.  You can take raloxifene only if you have already gone through menopause. You can take tamoxifen before or after menopause. 

Aromatase inhibitors  

Aromatase inhibitors are medications that stop a key enzyme (called aromatase) from changing other hormones into estrogen. Aromatase inhibitors are part of the standard treatment for breast cancer in women who have gone through menopause. One of these medications, exemestane, has also been shown to lower the risk of breast cancer in postmenopausal women at higher risk, including women with LCIS.

Prophylactic Mastectomy

Bilateral prophylactic (PRO-fih-LAK-tik) mastectomy is the surgical removal of both breasts to try to prevent breast cancer.  This surgery is seldom used to lower the risk of breast cancer in women with LCIS.
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